WASHINGTON (CNN) -- The newly released audiotape said to be of fugitive terrorism suspect Abu Musab Zarqawi is "probably authentic," according to a CIA assessment.

An intelligence official said references made in the tape suggest it was recorded "fairly recently."

On the audio tape, published Tuesday on a Web site, Al-Zarqawi claimed credit for a score of attacks on coalition forces, including the August 19 bombing of U.N. headquarters in Baghdad that killed 23 civilians including the U.N.'s chief envoy to Iraq, Sergio Vieira de Mello.

This is the first time Zarqawi has claimed responsibility for attacks. A U.S. official said that could indicate Zarqawi is "attempting to explain himself."

The official pointed to a number of references in the tape that are of interest, including taking credit for the bombings of the U.N. compound and of an Italian facility.

The official said the admissions are "in line" with what the intelligence community had thought to be "acts conducted by the Zarqawi organization."

Al-Zarqawi, an associate of Osama bin Laden, has been named by the Bush administration as an al Qaeda member who fled to Iraq from Afghanistan in 2002 to seek medical treatment.

The tape also contained threats to assassinate Gen. John Abizaid, commander of the U.S. Central Command in Iraq and Paul Bremer, the top U.S. civilian administrator in Iraq.

Al-Zarqawi was especially hostile toward the Shiite majority, calling them "idolaters" and traitors who allied themselves with "the enemies of Islam to seize control over Sunni Iraq."

The U.S. official noted how Zarqawi "grouped the Shia and the coalition together to justify attacks," citing historical references and quoting scholars. The official said this "suggests he is aiming his message to attract broader Sunni support."

However, the official said the CIA is unable to "draw a conclusion" on whether Zarqawi is working with elements of the former Saddam regime to destabilize Iraq and attack coalition forces.